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1 | /* |
2 | * simple driver for PWM (Pulse Width Modulator) controller |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify |
5 | * it under the terms of the GNU General Public License version 2 as |
6 | * published by the Free Software Foundation. |
7 | * |
8 | * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com> |
9 | */ |
10 | |
11 | #include <linux/module.h> |
12 | #include <linux/kernel.h> |
13 | #include <linux/platform_device.h> |
14 | #include <linux/slab.h> |
15 | #include <linux/err.h> |
16 | #include <linux/clk.h> |
17 | #include <linux/io.h> |
18 | #include <linux/pwm.h> |
19 | #include <mach/hardware.h> |
20 | |
21 | |
22 | /* i.MX1 and i.MX21 share the same PWM function block: */ |
23 | |
24 | #define MX1_PWMC 0x00 /* PWM Control Register */ |
25 | #define MX1_PWMS 0x04 /* PWM Sample Register */ |
26 | #define MX1_PWMP 0x08 /* PWM Period Register */ |
27 | |
28 | |
29 | /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */ |
30 | |
31 | #define MX3_PWMCR 0x00 /* PWM Control Register */ |
32 | #define MX3_PWMSAR 0x0C /* PWM Sample Register */ |
33 | #define MX3_PWMPR 0x10 /* PWM Period Register */ |
34 | #define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4) |
35 | #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16) |
36 | #define MX3_PWMCR_CLKSRC_IPG (1 << 16) |
37 | #define MX3_PWMCR_EN (1 << 0) |
38 | |
39 | |
40 | |
41 | struct pwm_device { |
42 | struct list_head node; |
43 | struct platform_device *pdev; |
44 | |
45 | const char *label; |
46 | struct clk *clk; |
47 | |
48 | int clk_enabled; |
49 | void __iomem *mmio_base; |
50 | |
51 | unsigned int use_count; |
52 | unsigned int pwm_id; |
53 | }; |
54 | |
55 | int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) |
56 | { |
57 | if (pwm == NULL || period_ns == 0 || duty_ns > period_ns) |
58 | return -EINVAL; |
59 | |
60 | if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25()) { |
61 | unsigned long long c; |
62 | unsigned long period_cycles, duty_cycles, prescale; |
63 | u32 cr; |
64 | |
65 | c = clk_get_rate(pwm->clk); |
66 | c = c * period_ns; |
67 | do_div(c, 1000000000); |
68 | period_cycles = c; |
69 | |
70 | prescale = period_cycles / 0x10000 + 1; |
71 | |
72 | period_cycles /= prescale; |
73 | c = (unsigned long long)period_cycles * duty_ns; |
74 | do_div(c, period_ns); |
75 | duty_cycles = c; |
76 | |
77 | writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR); |
78 | writel(period_cycles, pwm->mmio_base + MX3_PWMPR); |
79 | |
80 | cr = MX3_PWMCR_PRESCALER(prescale) | MX3_PWMCR_EN; |
81 | |
82 | if (cpu_is_mx25()) |
83 | cr |= MX3_PWMCR_CLKSRC_IPG; |
84 | else |
85 | cr |= MX3_PWMCR_CLKSRC_IPG_HIGH; |
86 | |
87 | writel(cr, pwm->mmio_base + MX3_PWMCR); |
88 | } else if (cpu_is_mx1() || cpu_is_mx21()) { |
89 | /* The PWM subsystem allows for exact frequencies. However, |
90 | * I cannot connect a scope on my device to the PWM line and |
91 | * thus cannot provide the program the PWM controller |
92 | * exactly. Instead, I'm relying on the fact that the |
93 | * Bootloader (u-boot or WinCE+haret) has programmed the PWM |
94 | * function group already. So I'll just modify the PWM sample |
95 | * register to follow the ratio of duty_ns vs. period_ns |
96 | * accordingly. |
97 | * |
98 | * This is good enough for programming the brightness of |
99 | * the LCD backlight. |
100 | * |
101 | * The real implementation would divide PERCLK[0] first by |
102 | * both the prescaler (/1 .. /128) and then by CLKSEL |
103 | * (/2 .. /16). |
104 | */ |
105 | u32 max = readl(pwm->mmio_base + MX1_PWMP); |
106 | u32 p = max * duty_ns / period_ns; |
107 | writel(max - p, pwm->mmio_base + MX1_PWMS); |
108 | } else { |
109 | BUG(); |
110 | } |
111 | |
112 | return 0; |
113 | } |
114 | EXPORT_SYMBOL(pwm_config); |
115 | |
116 | int pwm_enable(struct pwm_device *pwm) |
117 | { |
118 | int rc = 0; |
119 | |
120 | if (!pwm->clk_enabled) { |
121 | rc = clk_enable(pwm->clk); |
122 | if (!rc) |
123 | pwm->clk_enabled = 1; |
124 | } |
125 | return rc; |
126 | } |
127 | EXPORT_SYMBOL(pwm_enable); |
128 | |
129 | void pwm_disable(struct pwm_device *pwm) |
130 | { |
131 | writel(0, pwm->mmio_base + MX3_PWMCR); |
132 | |
133 | if (pwm->clk_enabled) { |
134 | clk_disable(pwm->clk); |
135 | pwm->clk_enabled = 0; |
136 | } |
137 | } |
138 | EXPORT_SYMBOL(pwm_disable); |
139 | |
140 | static DEFINE_MUTEX(pwm_lock); |
141 | static LIST_HEAD(pwm_list); |
142 | |
143 | struct pwm_device *pwm_request(int pwm_id, const char *label) |
144 | { |
145 | struct pwm_device *pwm; |
146 | int found = 0; |
147 | |
148 | mutex_lock(&pwm_lock); |
149 | |
150 | list_for_each_entry(pwm, &pwm_list, node) { |
151 | if (pwm->pwm_id == pwm_id) { |
152 | found = 1; |
153 | break; |
154 | } |
155 | } |
156 | |
157 | if (found) { |
158 | if (pwm->use_count == 0) { |
159 | pwm->use_count++; |
160 | pwm->label = label; |
161 | } else |
162 | pwm = ERR_PTR(-EBUSY); |
163 | } else |
164 | pwm = ERR_PTR(-ENOENT); |
165 | |
166 | mutex_unlock(&pwm_lock); |
167 | return pwm; |
168 | } |
169 | EXPORT_SYMBOL(pwm_request); |
170 | |
171 | void pwm_free(struct pwm_device *pwm) |
172 | { |
173 | mutex_lock(&pwm_lock); |
174 | |
175 | if (pwm->use_count) { |
176 | pwm->use_count--; |
177 | pwm->label = NULL; |
178 | } else |
179 | pr_warning("PWM device already freed\n"); |
180 | |
181 | mutex_unlock(&pwm_lock); |
182 | } |
183 | EXPORT_SYMBOL(pwm_free); |
184 | |
185 | static int __devinit mxc_pwm_probe(struct platform_device *pdev) |
186 | { |
187 | struct pwm_device *pwm; |
188 | struct resource *r; |
189 | int ret = 0; |
190 | |
191 | pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL); |
192 | if (pwm == NULL) { |
193 | dev_err(&pdev->dev, "failed to allocate memory\n"); |
194 | return -ENOMEM; |
195 | } |
196 | |
197 | pwm->clk = clk_get(&pdev->dev, "pwm"); |
198 | |
199 | if (IS_ERR(pwm->clk)) { |
200 | ret = PTR_ERR(pwm->clk); |
201 | goto err_free; |
202 | } |
203 | |
204 | pwm->clk_enabled = 0; |
205 | |
206 | pwm->use_count = 0; |
207 | pwm->pwm_id = pdev->id; |
208 | pwm->pdev = pdev; |
209 | |
210 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
211 | if (r == NULL) { |
212 | dev_err(&pdev->dev, "no memory resource defined\n"); |
213 | ret = -ENODEV; |
214 | goto err_free_clk; |
215 | } |
216 | |
217 | r = request_mem_region(r->start, r->end - r->start + 1, pdev->name); |
218 | if (r == NULL) { |
219 | dev_err(&pdev->dev, "failed to request memory resource\n"); |
220 | ret = -EBUSY; |
221 | goto err_free_clk; |
222 | } |
223 | |
224 | pwm->mmio_base = ioremap(r->start, r->end - r->start + 1); |
225 | if (pwm->mmio_base == NULL) { |
226 | dev_err(&pdev->dev, "failed to ioremap() registers\n"); |
227 | ret = -ENODEV; |
228 | goto err_free_mem; |
229 | } |
230 | |
231 | mutex_lock(&pwm_lock); |
232 | list_add_tail(&pwm->node, &pwm_list); |
233 | mutex_unlock(&pwm_lock); |
234 | |
235 | platform_set_drvdata(pdev, pwm); |
236 | return 0; |
237 | |
238 | err_free_mem: |
239 | release_mem_region(r->start, r->end - r->start + 1); |
240 | err_free_clk: |
241 | clk_put(pwm->clk); |
242 | err_free: |
243 | kfree(pwm); |
244 | return ret; |
245 | } |
246 | |
247 | static int __devexit mxc_pwm_remove(struct platform_device *pdev) |
248 | { |
249 | struct pwm_device *pwm; |
250 | struct resource *r; |
251 | |
252 | pwm = platform_get_drvdata(pdev); |
253 | if (pwm == NULL) |
254 | return -ENODEV; |
255 | |
256 | mutex_lock(&pwm_lock); |
257 | list_del(&pwm->node); |
258 | mutex_unlock(&pwm_lock); |
259 | |
260 | iounmap(pwm->mmio_base); |
261 | |
262 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
263 | release_mem_region(r->start, r->end - r->start + 1); |
264 | |
265 | clk_put(pwm->clk); |
266 | |
267 | kfree(pwm); |
268 | return 0; |
269 | } |
270 | |
271 | static struct platform_driver mxc_pwm_driver = { |
272 | .driver = { |
273 | .name = "mxc_pwm", |
274 | }, |
275 | .probe = mxc_pwm_probe, |
276 | .remove = __devexit_p(mxc_pwm_remove), |
277 | }; |
278 | |
279 | static int __init mxc_pwm_init(void) |
280 | { |
281 | return platform_driver_register(&mxc_pwm_driver); |
282 | } |
283 | arch_initcall(mxc_pwm_init); |
284 | |
285 | static void __exit mxc_pwm_exit(void) |
286 | { |
287 | platform_driver_unregister(&mxc_pwm_driver); |
288 | } |
289 | module_exit(mxc_pwm_exit); |
290 | |
291 | MODULE_LICENSE("GPL v2"); |
292 | MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>"); |
293 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
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